2-(Dicyanomethylene)croconate is a divalent anion with chemical formula C
4 or ((N≡C−)2C=)(C5O4)2−. It is one of the pseudo-oxocarbon anions, as it can be described as a derivative of the croconate oxocarbon anion C
5 through the replacement of one oxygen atom by a dicyanomethylene group =C(−C≡N)2.
The anion was synthesized and characterized by A. Fatiadi in 1980, by hydrolysis of croconate violet treated with potassium hydroxide. It gives an orange solution in water.